Compton X-ray and γ-ray Emission from Extended Radio Galaxies

We would like to present early results from the EINSTEIN X-ray Observatory on three radio galaxies: Centaurus A, NGC 315 = DW0055+30, and Cygnus A = 3C405. We hope to demonstrate that imaging X-ray astronomy can provide important insights into the physics and environment of radio galaxies and their extended radio components.NGC 5128, the parent galaxy of the double-double radio source Centaurus A, is the nearest radio galaxy, providing the best testing ground for high resolution X-ray studies. The X-ray morphology has proved to be rich and varied. We detect four distinct components to the X-ray emission: (1) the strong, compact nucleus detected by earlier satellites; (2) extended emission around the nucleus; (3) emission from the inner radio lobes; and (4) a unique X-ray jet between the nucleus and the NE radio lobe. A detailed presentation of these observations can be found in Schreier et al. (1979).

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Young radio sources at high-energies and the γ-ray CSO PKS 1718–649

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318003903 ◽

2018 ◽

Vol 14 (S342) ◽

pp. 176-179

Author(s):

Giulia Migliori

Keyword(s):

Radio Galaxy ◽

Radio Galaxies ◽

High Energy ◽

Radio Sources ◽

Host Galaxies ◽

X Ray ◽

High Energies ◽

Γ Rays ◽

Γ Ray ◽

High Energy Emission

AbstractObservations at high-energies are important to define the first stages of the evolution of extragalactic radio sources and to characterize the interstellar medium of their host galaxies. In some of the X-ray-observed Compact Symmetric Objects (CSOs, among the youngest and most compact radio galaxies), we measured values of the total hydrogen column densities large enough to slow or prevent the radio source growth. The γ-ray window has the potential to constrain the non-thermal contribution of jets and lobes to the total high-energy emission. However, so far, young radio sources remain elusive in γ-rays, with only a handful of detections (or candidates) reported by Fermi. I present our γ-ray study of the CSO PKS 1718–649, and draw comparison with the restarted, γ-ray detected, radio galaxy 3C 84.

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X-ray and γ-ray emissions from NLSy1 galaxies

International Journal of Modern Physics D ◽

10.1142/s0218271818440017 ◽

2018 ◽

Vol 27 (10) ◽

pp. 1844001 ◽

Cited By ~ 4

Author(s):

V. Baghmanyan ◽

N. Sahakyan

Keyword(s):

Spectral Properties ◽

Radio Galaxies ◽

Narrow Line ◽

High Luminosity ◽

Large Area ◽

X Ray ◽

Emission Properties ◽

Balmer Lines ◽

Γ Ray

The recent observations by Fermi large area telescope (Fermi-LAT) showed that in addition to the radio galaxies and blazars, Narrow-Line Seyfert 1 (NLSy1) galaxies are also [Formula: see text]-rays emitters. NLSy1 are AGNs with optical spectral properties similar to those of Seyfert 1 galaxies, except for having narrow Balmer lines and strong optical lines. They also exhibit strong X-ray variability, steep X-ray spectra and relatively high luminosity. The multiwavelength emission properties of 1H 0323+342, SBS 0846+513 and PMN J0948+0022 are discussed, using the [Formula: see text]-ray data from the last 8.8 years Fermi-LAT observations as well as available Swift(UVOT/XRT) data. It is shown that one-zone synchrotron/synchrotron self-Compton (SSC) model can satisfactorily reproduce their observed broadband spectra.

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Non-thermal emission in lobes of radio galaxies – III. 3C 98, Pictor A, DA 240, Cygnus A, 3C 326, and 3C 236

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3415 ◽

2019 ◽

Vol 491 (4) ◽

pp. 5740-5746 ◽

Cited By ~ 2

Author(s):

Massimo Persic ◽

Yoel Rephaeli

Keyword(s):

Thermal Emission ◽

Radio Galaxies ◽

Spectral Energy ◽

Large Area ◽

Microwave Background ◽

Extragalactic Background Light ◽

X Ray ◽

Radiation Fields ◽

Cygnus A ◽

Γ Ray

ABSTRACT Recent analyses of the broad spectral energy distributions (SEDs) of extensive lobes of local radio galaxies have confirmed the leptonic origin of their Fermi/Large Area Telescope γ-ray emission, significantly constraining the level of hadronic contribution. SEDs of distant (DL > 125 Mpc) radio-galaxy lobes are currently limited to the radio and X-ray bands, hence give no information on the presence of non-thermal (NT) protons but are adequate to describe the properties of NT electrons. Modelling lobe radio and X-ray emission in 3C 98, Pictor A, DA 240, Cygnus A, 3C 326, and 3C 236, we fully determine the properties of intralobe NT electrons and estimate the level of the related γ-ray emission from Compton scattering of the electrons off the superposed cosmic microwave background, extragalactic background light, and source-specific radiation fields.

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Radio morphology–accretion mode link in Fanaroff–Riley type II low-excitation radio galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa560 ◽

2020 ◽

Vol 493 (3) ◽

pp. 4355-4366 ◽

Cited By ~ 2

Author(s):

D Macconi ◽

E Torresi ◽

P Grandi ◽

B Boccardi ◽

C Vignali

Keyword(s):

Accretion Rate ◽

Control Sample ◽

Radio Galaxies ◽

Optical Data ◽

Type Ii ◽

Nuclear Excitation ◽

Complete Sample ◽

X Ray ◽

Extended Radio ◽

Accretion Rates

ABSTRACT Fanaroff–Riley type II (FR II) low-excitation radio galaxies (LERGs) are characterized by weak nuclear excitation on parsec-scales and properties typical of powerful FR IIs (defined as high-excitation radio galaxies, hereafter HERGs/BLRGs) on kiloparsec-scales. Since a link between the accretion properties and the power of the produced jets is expected both from theory and observations, their nature is still debated. In this work, we investigate the X-ray properties of a complete sample of 19 FR II-LERGs belonging to the 3CR catalogue, exploiting Chandra and XMM–Newton archival data. We also analyse 32 FR II-HERGs/BLRGs with Chandra data as a control sample. We compared FR II-LERG and FR II-HERG/BLRG X-ray properties and optical data available in literature to obtain a wide outlook of their behaviour. The low accretion rate estimates for FR II-LERGs, from both X-ray and optical bands, allow us to firmly reject the hypothesis as they are the highly obscured counterpart of powerful FR II-HERGs/BLRGs. Therefore, at least two hypothesis can be invoked to explain the FR II-LERG nature: (i) they are evolving from classical FR IIs because of the depletion of accreting cold gas in the nuclear region, while the extended radio emission is the heritage of a past efficiently accreting activity; and (ii) they are an intrinsically distinct class of objects with respect to classical FR Is/FR IIs. Surprisingly, in this direction, a correlation between accretion rates and environmental richness is found in our sample. The richer the environment is, the more inefficient is the accretion. In this framework, the FR II-LERGs are intermediate between FR Is and FR II-HERGs/BLRGs both in terms of accretion rate and environment.

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